It is known that the life expentancy of the impactor of an impact ripper is increased by having the hydraulic impactor deliver impact blows to the ripper shank only when the ripper shank is loaded above a predetermined level so the impact energy is substantially fully transmitted into the material being ripped. If the ripper shanks are not sufficiently loaded, the impact energy is absorbed by the impactor and/or ripper structure and leads to early failures thereto. A previous control system for a single shank impact ripper determines the load on the ripper shank by sensing the hydraulic pressure in a hydraulic cylinder used to control the pitch of the ripper shank. If the hydraulic pressure of the hydraulic cylinder is below a predetermined level, the hydraulic impactor cannot be automatically activated. Also, that system has single pump dedicated to the hydraulic impactor at least when the impactor is in operation so that operating speed of the impactor is a function of the output of the pump. While that system was acceptable for an impact ripper having a single shank and single hydraulic impactor, it is not acceptable for use with an impact ripper having a plurality of shanks and hydraulic impactors wherein the position of all the ripper shanks is controlled by one or more common hydraulic cylinders working in unison. Moreover, that system was not capable of controlling the output flow from a pair of pumps necessary for the operation of a plurality of hydraulic impactors.
The present invention is directed to overcoming one or more of the problems as set forth above.